This invention relates to both a semiconductor device for detecting a strength of a magnetic field and a producing method thereof, and more particularly a Group III and V element compound semiconductor layer formed on a single element semiconductor wafer such as silicon wafer.
It is well known that a Group III and V element compound semiconductor such as gallium arsenide GaAs is used in diversified devices including Hall-effect devices, high-performance transistors, laser diodes, light-emitting diodes, photo-transistors, photo-diodes and solar cells because of the high-mobility, the direct-transition band structure and the variable character regarding its band gap and lattice.
However, according to the conventional skill, since it is not easy to manufacture a single crystal gallium arsenide device having a large diameter, it is difficult to integrate the gallium arsenide device and other circuits into a gallium arsenide wafer. This has lead to a high production cost.
For the above-mentioned problem, another approach is proposed by the present applicant (PCT Application No. JP89/0049; U.S. filing date Mar. 29, 1990). Namely, it relates to a composite integrated circuit which includes a Hall-effect element formed of gallium arsenide formed on a silicon wafer together with other circuits.
However, the research conducted by the inventors of the present invention have determined a problem about such hetero-epitaxial growth of gallium arsenide on the silicon wafer.
Specifically, hetero-epitaxial growth of gallium arsenide is done on a silicon wafer by using a metal organic chemical vapor deposition, so-called MOCVD. The gallium arsenide layer is then etched with photolithography by tartaric acid or another etching fluid such as sulfuric acid. In this etching process, the inventors of the present invention noticed that the shape of the gallium arsenide layer becomes asymmetric due to an etching velocity anisotropy of the etching fluid. This geometrical unbalance of the gallium arsenide layer is believed to result in an unbalanced voltage.